Before the rise of the Imperium or even the emergence of Mankind into the galaxy, the Eldar had established a mighty civilization that spanned many planetary systems. Their huge citiships and craft-worlds, vast ornate palaces floating between star systems, traded new knowledge and goods. Learning, enlightenment and reason flourished. The Eldar enriched the galaxy and looked for new worlds to make their own and new challenges to meet.

One challenge they took up was the complete mastery of warp-gate technology. The Eldar adopted, refined and perfected the ancient Slaan knowledge of the warp and its movements. They established a network of wormhole tunnels through warpspace, linking gates aboard their craft-worlds, planets and smaller spaceships. It was possible for an Eldar to walk from one planet to another, across hundreds or thousands of light-years of real space. The warp-gates bound the Eldar together as a single civilization, stretching across space and, it was theorized, backwards and forwards in time. The Eldar, fearful of the consequences, never experimented with the temporal aspect of warp-gates.

Their studies did, however, bring them an understanding of the link between the warp and psychic power. In making this conceptual leap, the Eldar also discovered the power of Chaos, in all its seductive glory. The Eldar, for all their apparent culture, had never encountered its like. Some turned from the warp with disgust when the corrupting nature of Chaos and its effects on reality became evident, but others responded with new vigour. The manifestations of Chaos - insanity, wickedness and depravity - spread like wildfire through the Eldar and was carried further by tainted individuals with access to the warp-gates. In the space of a single generation the Eldar paused in their quest for enlightenment and chose the darker path into the service of Chaos.

Eldar who remained untouched by Chaos, retreated to the citiships and larger craft-worlds. The insanity of Chaos had no foothold or appeal aboard the vast ships. The warp-gates to the infected Eldar worlds were closed and locked. The citiships were absorbed into the larger craft-worlds, and all drifted into the depths of space, lifeboats and seed-pods of civilization.

The rest of their race sank wholeheartedly into the dark worship of the Chaos gods. A racial madness had taken hold throughout Eldar space ad the insanity had only one end. In a mindless psychic orgy every Eldar planet perished in a single night. The death screams of the Eldar echoed across the warp. On every planet Eldar corpses twitched in the mindless dance of Chaos and crumbled to dust. Worlds were laid waste in moments. The Eldar race were sucked into the warp.

The dead Eldar, however, were not gone. Their spirits had merged with the warp in a horrifying manner. Their death-shout became a howl of joy and release. Slaanesh, the Lord of Pleasure, god of unbridled depravity, was born from the dark side of Eldar nature. The psychic pain of the Eldar's racial death and Slaanesh's birth convulsed the warp; the warp storms around Earth were blown away, and warpspace itself rippled into new patterns.

The last of the Eldar drifted into the long night between the stars. The racial memory of their former glory and nobility sustained them, while the downfall of the race filled them with bitterness. They had come face-to-face with their darkest desires and been found wanting.

For them, Mankind is a reminder of what happened long ago. Humanity is treading the same path toward the darkness of Chaos, a crude mirror of the Eldar's own disgrace. They are burdened by racial shame for the weakness of their failed ancestors. The bright hopeful universe is a place of stark, gibbering horror, and the Eldar fell when confronted with this truth. Surviving Eldar have grown since then, accepting and holding in check the Chaos that lurks within their hearts, a delicate balancing act that they seem to have mastered at last.

Mankind rushes towards the fate of the Eldar, but without the ability to preserve itself in any form. All the signs are there to be read: humanity's moral leprosy of Chaos worship, its rising number of emergent psykers, its lust for universal power, and its fragile, failing Emperor...